Spy Tech: I see what you write

Martin Brinkmann
May 19, 2008
Updated • Nov 12, 2017

Two new techniques to spy on computer users have been revealed these days by two independent scientific studies conducted at the University of California, Santa Barbara, and at Saarland University in Saarbrucken, Germany.

The researchers in California developed an algorithm that estimates what is written on a  computer by watching the hands of the person writing (without seeing what is on the screen or which keys the fingers tap on). The algorithm is far from perfect and has a success rate of 40% right now; this is usually enough to understand the general meaning of the text.

Words are chosen by probability, and alternatives are suggested which may make more sense than the first word and help the reader in understanding the meaning of a sentence or phrase.

The new observation method introduces a new technique to spy on users without actually seeing the computer screen or the computer keyboard. All that is required is to have a good view of the hands of the individual and a measurement of the keyboard.

The second spy tech could come right out of the latest James Bond movie. Researchers at Saarland University managed to write a computer algorithm that is capable of interpreting reflections of the computer screen on objects. The quality of the telescope plays an important role, a normal $500 telescope was able to read 12 point fonts of a reflection that was 5 meters away from the computer and 198 point fonts from a distance of ten meters.

A more powerful Dobson telescope for $27500 yielded the same results from a maximum distance of 30 meters. Other tests allowed the researchers to view the monitor from a white wall that was 2 meters away from the computer screen.

The best way to defeat the techniques? Don't access a computer in public, always close the curtains when working with your computer and make sure no cameras are installed in the room with a computer.

Article Name
Spy Tech: I see what you write
Two new techniques to spy on computer users have been revealed these days by two independent scientific studies.
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  1. Anonymous said on December 17, 2008 at 1:49 am


  2. Tobey said on May 20, 2008 at 7:53 pm

    Shall we start building separate solid shelters to achieve better privacy when working on our computer? Might be the case soon :D

  3. Martin said on May 20, 2008 at 10:00 am

    you forgot to mention the lead walls. Oh yeah, I just discovered why your wireless connection is not working ;)

  4. Grimskallen said on May 20, 2008 at 9:59 am

    Best way to beat the technique?
    Live in a bunker without windows, with autolock… *Put pictures of my office here*

  5. Transcontinental said on May 20, 2008 at 12:45 am

    And avoid voice recognition without intimacy !

  6. Rarst said on May 20, 2008 at 12:19 am

    My opinion: if someone who has cash for 27500$ telescope is interested in your computer – closing curtains is so not going to help. :)

    Military is using kinda tents that block optical and EM spying (don’t know about sound) but I doubt you can just go and buy it.

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